Aqueous ink composition

Abstract

The present invention addresses the problem of providing an aqueous ink composition which has excellent adhesiveness to polyester film substrates and / or polyamide film substrates. The problem is solved with an aqueous ink composition comprising (A) a vinyl-chloride-based resin emulsion and / or an acrylic resin emulsion and (B) an aqueous polyester resin.

Description

Water-based ink composition

[0001] The present invention relates to an aqueous ink composition.

[0002] Vinyl chloride resins are used in a variety of applications due to their excellent chemical resistance, water resistance, weather resistance, flame retardancy, processability, and colorability. Known examples of such applications include paints and inks. For example, Patent Document 1 describes a primer ink for inkjet recording that contains an acrylic-vinyl chloride emulsion, a hydrazine derivative having at least two hydrazine residues, and water.

[0003] Japanese Patent Publication No. 2018-12219

[0004] Incidentally, substrates on which ink is used include not only absorbent substrates such as paper but also poorly absorbent substrates such as film. In particular, there are various types of film substrates. However, in the above-mentioned conventional techniques, depending on the type of film substrate, the ink adhesion to the film substrate is insufficient, leaving room for improvement.

[0005] An object of one aspect of the present invention is to provide an aqueous ink composition that has excellent adhesion to at least one film substrate selected from the group consisting of polyester substrates and polyamide substrates.

[0006] In order to solve the above problems, an aqueous ink composition according to one embodiment of the present invention contains (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin.

[0007] According to one aspect of the present invention, it is possible to provide an aqueous ink composition that has excellent adhesion to at least one film substrate of a polyester substrate and a polyamide substrate.

[0008] One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included within the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)." Furthermore, "(meth)acrylic..." is intended to include both "methacrylic..." and "acrylic...."

[0009] 1. Aqueous Ink Composition An aqueous ink composition according to one embodiment of the present invention contains (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin.

[0010] 1-1. Component (A) The aqueous ink composition according to one embodiment of the present invention contains a vinyl chloride resin emulsion and / or an acrylic resin emulsion as component (A).

[0011] [1-1-1. Vinyl chloride resin emulsion] A "vinyl chloride resin emulsion" refers to an emulsion of a "vinyl chloride resin," and a "vinyl chloride resin" refers to a resin obtained by polymerizing a monomer mixture containing vinyl chloride monomer. The "vinyl chloride resin" may be any resin obtained by polymerizing a monomer mixture containing vinyl chloride monomer, but is preferably a resin obtained by polymerizing a monomer containing, for example, 30 parts by weight or more, more preferably 40 parts by weight or more, and even more preferably 45 parts by weight or more of vinyl chloride monomer, based on 100 parts by weight of the total monomer mixture. There is no particular upper limit to the amount of vinyl chloride monomer contained in the total monomer mixture, as long as it is 100 parts by weight or less.

[0012] The "vinyl chloride resin" is not particularly limited, but examples thereof include vinyl chloride resin, vinyl chloride-acrylic composite resin, vinyl chloride-acrylic copolymer, vinyl chloride-urethane composite resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, and vinyl chloride-vinylidene chloride copolymer. Herein, "vinyl chloride resin" refers to a resin primarily composed of vinyl chloride, preferably a resin containing more than 90 parts by weight and up to 100 parts by weight of vinyl chloride monomer, based on 100 parts by weight of the total monomer mixture. That is, in this specification, "vinyl chloride resin" includes polyvinyl chloride containing only vinyl chloride monomer, and vinyl chloride-based resins containing more than 90 parts by weight and up to 100 parts by weight of vinyl chloride monomer. Furthermore, "acrylic-containing resin" refers to a resin primarily composed of acrylic, preferably a resin containing 50 to 100 parts by weight of an acrylic monomer, based on 100 parts by weight of the total monomer mixture.

[0013] The "vinyl chloride resin emulsion" is not limited to any emulsion of a "vinyl chloride resin." For example, a "vinyl chloride resin emulsion" produced by emulsion polymerization may be used as is. Alternatively, a vinyl chloride resin produced by another method may be forcibly emulsified in water using a surfactant or the like. Furthermore, a self-emulsifying emulsion may be prepared by copolymerizing a vinyl chloride resin with a monomer having a hydrophilic group, adding water to the resulting hydrophilic group-containing vinyl chloride resin, and then emulsifying the resulting vinyl chloride resin.

[0014] [1-1-1-1. Vinyl chloride-acrylic composite resin emulsion] Examples of the vinyl chloride-acrylic composite resin emulsion include a resin emulsion of a resin obtained by polymerizing an acrylic monomer in the presence of a vinyl chloride resin, a resin emulsion of a resin obtained by polymerizing a vinyl chloride monomer in the presence of an acrylic-containing resin, and a resin emulsion of a resin obtained by polymerizing a vinyl chloride monomer in the presence of a styrene-(meth)acrylic acid ester oligomer and / or a (meth)acrylic acid ester oligomer.

[0015] <Resin emulsion of composite resin obtained by polymerizing acrylic monomer in the presence of vinyl chloride resin> An example of the resin obtained by polymerizing an acrylic monomer in the presence of vinyl chloride resin is a vinyl chloride-acrylic composite resin obtained by polymerizing a monomer mainly composed of vinyl chloride monomer in the first stage (hereinafter referred to as [Step 1]) in a multistage emulsion polymerization method, and polymerizing a monomer mainly composed of acrylic monomer in the second stage and thereafter (hereinafter referred to as [Step 2]).

[0016] The vinyl chloride-acrylic composite resin is, for example, a multistage emulsion polymerization method in which, as "step 1," (a1) vinyl chloride monomer is more than 90 parts by weight and 100 parts by weight or less, and (a2) an ethylenically unsaturated monomer copolymerizable with vinyl chloride monomer is 0 to 10 parts by weight. In the presence of a vinyl chloride resin obtained by polymerizing a monomer mixture (wherein the total amount of (a1) and (a2) is 100 parts by weight), [step 2] is (b1) (meth) acrylic acid alkyl ester 50 to 100 parts by weight, and (b2) an ethylenically unsaturated monomer copolymerizable with (b1) (meth) acrylic acid alkyl ester. A monomer mixture (wherein the total amount of (b1) and (b2) is 100 parts by weight) is a resin obtained by polymerizing a composite acrylic-containing resin obtained by polymerizing.

[0017] The mechanism is thought to be that the monomers constituting the acrylic-containing resin penetrate into the vinyl chloride resin particles obtained in [Step 1] and polymerize within the vinyl chloride resin particles, so that the vinyl chloride resin and the acrylic-containing resin are entangled rather than forming a distinct core / shell structure within the particles. Examples of such vinyl chloride-acrylic composite resins include the vinyl chloride-acrylic composite resins described in International Publication WO 2023 / 171695.

[0018] (Vinyl chloride resin) The vinyl chloride resin is obtained by emulsion polymerization of a monomer mixture consisting of (a1) more than 90 parts by weight and not more than 100 parts by weight of vinyl chloride monomer and (a2) 0 to less than 10 parts by weight of an ethylenically unsaturated monomer copolymerizable with the vinyl chloride monomer, and is polymerized as the first stage of a multi-stage emulsion polymerization. [Step 1] may be carried out in one step or in multiple steps. When carried out in multiple steps, the composition of the monomer mixture may be changed in each step.

[0019] The amount of (a2) used is preferably 0 to less than 10 parts by weight, more preferably 0 to 5 parts by weight. The amount of (a1) used is preferably more than 90 parts by weight but not more than 100 parts by weight, more preferably 95 to 100 parts by weight.

[0020] The ethylenically unsaturated monomer (a2) copolymerizable with the vinyl chloride monomer used in [Step 1] is not particularly limited, and may be any known monomer copolymerizable with vinyl chloride. These ethylenically unsaturated monomers (a2) copolymerizable with the vinyl chloride monomer may be used alone or in combination of two or more.

[0021] In [Step 1], (F) a compound having at least two non-conjugated double bonds can also be used in combination for the purpose of crosslinking the vinyl chloride resin and / or introducing grafting points with the acrylic-containing resin in [Step 2].

[0022] The compound (F) having at least two non-conjugated double bonds used in [Step 1] is not particularly limited, and examples thereof include allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl fumarate, diallyl maleate, diallyl phthalate, triallyl trimellitate, trimethylolpropane diallyl ether, divinyl adipate, divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene dimethacrylate, monoethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol diacrylate, polyethylene glycol diacrylate, and bisphenol-modified polyethylene glycol diacrylate.

[0023] In particular, when the purpose is to introduce grafting points with an acrylic-containing resin in [Step 2], the compound (F) having at least two non-conjugated double bonds is preferably a compound having two or more allyl groups, and particularly preferably triallyl cyanurate (TAC), triallyl isocyanurate, or triallyl trimellitate, each of which has three allyl groups. These compounds (F) having at least two non-conjugated double bonds may be used alone or in combination of two or more.

[0024] The amount of (F) compound having at least two non-conjugated double bonds used is preferably 5 parts by weight or less, more preferably 1 part by weight or less, and even more preferably 0.3 parts by weight or less, per 100 parts by weight of the total of (a1) vinyl chloride monomer and (a2) ethylenically unsaturated monomer copolymerizable with vinyl chloride monomer. If the amount of (F) used is 5 parts by weight or less, the degree of crosslinking of the vinyl chloride resin does not become too high, so the penetration of the acrylic monomer polymerized in [Step 2] is less likely to be hindered. Therefore, intra-particle compounding proceeds favorably. Furthermore, by using (F) within the above range, adhesion inhibition is less likely to occur because the acrylic-containing resin is chemically bonded to the vinyl chloride resin, and adhesion to polyvinyl chloride substrates can be ensured when used as a coating film.

[0025] In the emulsion polymerization in [Step 1], an ionic or nonionic surfactant that is commonly used in emulsion polymerization methods can be used.

[0026] The amount of the surfactant used in [Step 1] is preferably 10 parts by weight or less, more preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the total amount of the vinyl chloride resin monomer mixture.

[0027] In [Step 1], it is more preferable to use a reactive surfactant (H) having a polymerizable double bond in one molecule as part or all of the surfactant used, in terms of suppressing the generation of new particles during emulsion polymerization and improving the water resistance and weather resistance of the resulting coating film. In particular, the use of a reactive surfactant having a polyoxyalkylene group in the molecule can improve the mechanical stability of the resulting resin emulsion.

[0028] Examples of the reactive surfactant (H) having a polymerizable double bond in one molecule used in [Step 1] include Adeka Reasop (registered trademark) ER-10, ER-20, ER-30, ER-40, SR-05, SR-10, SR-20, SR-1025, SR-2025, SR-3025, NE-10, NE-20, NE-30, NE-40, and SE-10N, manufactured by ADEKA CORPORATION; Antox (registered trademark) MS-60, RMA-1120, RMA-564, RMA-568, and RMA-506, manufactured by Nippon Nyukazai Co., Ltd.; and Aqualon (registered trademark) K, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. H-05, KH-10, RN-20, RN-30, RN-50, RN-2025, HS-10, HS-20, HS-1025, BC05, BC10, BC0515, BC1025, AR-10, AR-20, AR-1025, AR-2020, AN-10, AN-20, AN-30, AN-5065; Eleminol (registered trademark) JS-2, JS-20, RS-30, RS-3000 manufactured by Sanyo Chemical Industries, Ltd.; and Latemul (registered trademark) S-180, S-180A, PD-104, PD-420, PD-430, PD-430S manufactured by Kao Corporation.

[0029] As the polymerization initiator used in [Step 1], for example, the polymerization initiators described in International Publication WO2023 / 171695 can be suitably used.

[0030] (Acrylic-containing resin) The acrylic-containing resin is produced by polymerizing an acrylic monomer mixture in [Step 2] in the presence of the vinyl chloride resin obtained in [Step 1] and compounding it with the vinyl chloride resin, thereby imparting various functions to the resin.

[0031] The mechanism is thought to be that the monomers constituting the acrylic-containing resin penetrate into the vinyl chloride resin particles present in the system and polymerize within the particles, causing the vinyl chloride resin and the acrylic-containing resin to become entangled within the particles.

[0032] According to the above-mentioned configuration, by adjusting the monomer composition constituting the acrylic resin and changing the balance of hydrophilicity and hydrophobicity, it is possible to arbitrarily adjust the location of the acrylic resin within the particle. That is, if the acrylic resin is made to have a more hydrophobic composition than the vinyl chloride resin, it is thought that it can be more present near the inner side of the particle, and conversely, if it is made to have a more hydrophilic composition than the vinyl chloride resin, it is thought that it can be more present near the outer side of the particle. Furthermore, if the acrylic resin is made to have the same hydrophilicity and hydrophobicity as the vinyl chloride resin, it is thought that the acrylic resin and the vinyl chloride resin will be present in nearly uniform locations.

[0033] [Step 2] may be carried out in one step or in multiple steps. When the step is carried out in multiple steps, the composition of the monomer mixture may be changed for each step. The polymerization composition of the acrylic-containing resin in [Step 2] is composed of 50 to 100 parts by weight of (b1) an alkyl (meth)acrylate ester and 0 to 50 parts by weight of (b2) an ethylenically unsaturated monomer copolymerizable with the alkyl (meth)acrylate ester (here, the total amount of (b1) and (b2) is 100 parts by weight).

[0034] Specific examples of the (b1) (meth)acrylic acid alkyl ester used in [Step 2] include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, etc. These (b1) (meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

[0035] The ethylenically unsaturated monomer (b2) copolymerizable with the (meth)acrylic acid alkyl ester used in [Step 2] is not particularly limited as long as it is copolymerizable with the (meth)acrylic acid alkyl ester (b1). Specific examples of (b2) include aromatic hydrocarbon vinyl monomers such as styrene, α-methylstyrene, chlorostyrene, 4-hydroxystyrene, and vinyltoluene; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatate; allyl compounds; nitrile group-containing vinyl monomers such as (meth)acrylonitrile; macromonomers such as AS-6, AN-6, AA-6, AB-6, and AK-5 manufactured by Toagosei Co., Ltd.; vinyl methyl ether, propylene, butadiene, vinyl chloride, and vinylidene chloride. These ethylenically unsaturated monomers copolymerizable with the (meth)acrylic acid alkyl ester (b2) may be used alone or in combination of two or more.

[0036] Vinyl monomers having an acid group can also be used as (b2) in [Step 2] of the present invention. The presence of an acid group can improve the mechanical and chemical stability of the resulting resin emulsion and its adhesion to a substrate when used as a coating film.

[0037] Specific examples of the vinyl monomer having an acid group include unsaturated carboxylic acids and acid anhydrides thereof, such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, maleic anhydride, and itaconic anhydride, and monomers having a sulfonic acid group, such as sodium styrenesulfonate, sodium 2-sulfoethyl methacrylate, ammonium 2-sulfoethyl methacrylate, acrylamido tert-butylsulfonic acid, and sodium acrylamido tert-butylsulfonate. The vinyl monomer having an acid group may be used alone or in combination of two or more.

[0038] The amount of the vinyl monomer having an acid group used is preferably 0.2 to 10 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 1 to 5 parts by weight, based on 100 parts by weight of the total amount of the monomer mixture constituting the vinyl chloride resin and the acrylic-containing resin. When the amount of the vinyl monomer having an acid group used is 0.2 parts by weight or more, the mechanical stability and chemical stability of the resulting resin emulsion are excellent, and when the amount is 10 parts by weight or less, a sudden increase in emulsion viscosity and a decrease in water resistance can be prevented.

[0039] A vinyl monomer having a hydroxyl group can also be used as (b2) in [Step 2]. The presence of a hydroxyl group is preferable in that it improves the dispersibility of the pigment and allows the introduction of crosslinking points with isocyanate, melamine, etc.

[0040] A vinyl monomer having a polyoxyalkylene chain can also be used as (b2) used in [Step 2]. The presence of a polyoxyalkylene chain is preferred in that it improves the mechanical and chemical stability of the resulting resin emulsion even when a vinyl monomer having an acid group is not used.

[0041] The aforementioned (F) compound having at least two non-conjugated double bonds can be used as (b2) used in [Step 2]. In this case, the resulting particles have a crosslinked structure inside, improving the water resistance of the resulting coating film.

[0042] The amount of the compound (F) having at least two non-conjugated double bonds used is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 5 parts by weight, and even more preferably 1 to 3 parts by weight, based on 100 parts by weight of the total amount of the monomer mixture constituting the acrylic-containing resin.

[0043] By using a fluorine-containing vinyl monomer as (b2) used in [Step 2], it is possible to impart high water and oil repellency.

[0044] By using a monomer having an alkoxysilyl group as (b2) used in [Step 2], it is possible to impart crosslinkability and improve adhesion to glass, metals, etc.

[0045] The vinyl monomer having a hydroxyl group, the vinyl monomer having a polyoxyalkylene chain, the fluorine-containing vinyl monomer, and the monomer having an alkoxysilyl group described above as (b2) used in [Step 2] may be preferably selected from the monomers exemplified in International Publication WO 2023 / 171695. The amounts of these monomers used may also be within the ranges described in the publication.

[0046] Furthermore, by using an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group as (b2) used in [Step 2], adhesion to the film can be improved. Specific examples of the ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group include acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, and vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone). Of these, diacetone acrylamide and diacetone methacrylamide are particularly preferred in terms of reactivity, availability, and economy. The ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group may be used alone or in combination of two or more.

[0047] The amount of the ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group used is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the total monomer mixture constituting the acrylic-containing resin.

[0048] In step 2, an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group is used as (b2) to obtain an acrylic-containing resin, which is then compounded with a vinyl chloride resin. Then, a hydrazine derivative having at least two hydrazino or semicarbazide groups per molecule (C) can be added to the resulting emulsion to impart crosslinkability. This improves the water resistance, solvent resistance, and adhesion of the resulting coating film, ink, etc.

[0049] Specific examples of the (C) hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule include saturated aliphatic carboxylic acid dihydrazides having 2 to 18 carbon atoms, such as oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide; monocarboxylic acid dihydrazides, such as maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide; Olefinically unsaturated dicarboxylic acid dihydrazides; phthalic, terephthalic or isophthalic acid dihydrazides, and pyromellitic acid dihydrazides, trihydrazides or tetrahydrazides; nitrilotriacetic acid trihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide; carboxylic acid lower alkyl ester groups Polyhydrazides obtained by reacting a low polymer having the above structure with hydrazine or hydrazine hydrate (see Japanese Patent Publication No. 52-22878); carbonic acid dihydrazide, bissemicarbazide; polyfunctional semicarbazides obtained by reacting diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate and polyisocyanate compounds derived therefrom with an excess of dihydrazine compounds and / or the above-mentioned dihydrazides. Examples of the dihydrazide include aqueous polyfunctional semicarbazides obtained by reacting an excess of the dihydrazides listed above with isocyanate groups in a reaction product of the polyisocyanate compound with an active hydrogen compound containing a hydrophilic group, such as a polyether polyol or a polyethylene glycol monoalkyl ether; or mixtures of the polyfunctional semicarbazides listed above with aqueous polyfunctional semicarbazides (see JP-A-8-151358 and JP-A-8-245878). The (C) hydrazine derivatives having at least two hydrazino groups or semicarbazide groups per molecule may be used alone or in combination of two or more.

[0050] The amount of the (C) hydrazine derivative having a hydrazino group or a semicarbazide group to be blended is preferably such that the total amount of functional groups selected from hydrazide groups, semicarbazide groups, and hydrazone groups is 0.01 mol to 2 mol, and more preferably 0.05 mol to 1.5 mol, per 1 mol of carbonyl groups in the acrylic-containing resin.

[0051] That is, the vinyl chloride-acrylic composite resin emulsion has a carbonyl group derived from a keto group or an aldehyde group, and more preferably further contains (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule.

[0052] On the other hand, if the acrylic-containing resin in [Step 2] becomes too hydrophilic, it will concentrate near the particle surface, and the interface with the vinyl chloride resin will become clear, which may make it difficult to achieve the desired modification effect or may cause a sudden increase in emulsion viscosity.

[0053] Therefore, from the viewpoint of reducing the viscosity of the emulsion, it is more desirable that 60 parts by weight or more, more preferably 80 parts by weight or more, per 100 parts by weight of the total monomer mixture constituting the acrylic-containing resin, be a hydrophobic monomer having a solubility in water of less than 5 g / L at 20° C. If the ratio of the hydrophobic monomer is 60 parts by weight or more, the acrylic-containing resin does not concentrate near the particle surface, making it easier to express the properties of the vinyl chloride resin, and also reducing the emulsion viscosity, thereby improving productivity and economy.

[0054] In this specification, the water solubility of a monomer is the value described in the SDS of the manufacturer. The water solubility (evaluation temperature) of main monomers is shown below. Vinyl chloride: 8.8 g / L (25°C) Butyl methacrylate: 0.36 g / L (20°C) t-Butyl methacrylate: 0.36 g / L (25°C) Methyl methacrylate: 15.3 g / L (20°C) Styrene: 0.32 g / L (25°C) Butyl acrylate: 1.7 g / L (20°C) 2-Ethylhexyl acrylate: 0.025 g / L (30°C) Methacrylic acid: ∞ Diacetone acrylamide: 100 g or more / 100 g Note that, because solubility in water decreases as the dissolution temperature decreases, when the evaluation temperature for the value listed in the manufacturer's SDS is 20°C or higher, the solubility at 20°C was considered to be below the listed value.

[0055] In order to improve impact resistance, flexibility, and film-forming properties, it is preferable that the glass transition temperature (hereinafter referred to as "Tg") of the acrylic-containing resin is set lower than the Tg of the vinyl chloride resin.

[0056] Here, the glass transition temperature (Tg) of the resin obtained by polymerizing the monomer mixture is calculated by the following Fox formula: 1 / Tg=Σ(Wn / Tgn) / 100 In the formula, Wn represents the weight percent of monomer n, and Tgn represents the Tg (absolute temperature) of the homopolymer consisting of monomer n.

[0057] The Tg values ​​of major homopolymers are as follows: Vinyl chloride: 80°C, Butyl methacrylate: 20°C, t-butyl methacrylate: 107°C, Methyl methacrylate: 105°C, Styrene: 100°C, Butyl acrylate: -54°C, 2-Ethylhexyl acrylate: -70°C, Methacrylic acid: 144°C, Diacetone acrylamide: 77°C.

[0058] The surfactant and polymerization initiator used in the polymerization of the acrylic-containing resin in [Step 2] may be the same as those used in the polymerization of the vinyl chloride resin in [Step 1].

[0059] As in the polymerization of vinyl chloride resin in [Step 1], it is also preferable to use a reactive surfactant (H) having a polymerizable double bond in one molecule as part or all of the surfactant in [Step 2] in terms of suppressing the generation of new particles, water resistance, and weather resistance. In particular, when a reactive surfactant having a polyoxyalkylene group in the molecule is used, mechanical stability can be improved.

[0060] As the polymerization initiator used in [Step 2], a redox type polymerization initiator which is a combination of an organic peroxide, an oxidation-reduction catalyst and a reducing agent is particularly preferred from the viewpoint of polymerization stability and water resistance.

[0061] In the vinyl chloride-acrylic composite resin, the weight ratio of the vinyl chloride resin to the acrylic-containing resin is preferably 95:5 to 20:80, and more preferably 70:30 to 30:70, from the viewpoints of adhesion, impact resistance, flexibility, and film-forming properties.

[0062] The average particle size of the vinyl chloride-acrylic composite resin after completion of [Step 2] is preferably 20 nm to 500 nm, more preferably 50 nm to 300 nm, as measured by dynamic light scattering. An average particle size of 20 nm or more of the composite resin particles is preferred because it reduces viscosity and improves stability, while an average particle size of 500 nm or less is preferred because it provides excellent water resistance. Furthermore, when the vinyl chloride-acrylic composite resin emulsion is directly used to produce ink, it is more preferred to adjust the average particle size of the composite resin particles to 60 nm to 120 nm. This results in particularly good adhesion, water resistance, and water-whitening resistance. The average particle size can be adjusted by the amount of surfactant added at the beginning of [Step 1].

[0063] The composite resin particles obtained by the present invention can be used as they are in the form of an emulsion, or can be dried and used as a powder.

[0064] <Resin emulsion of a composite resin obtained by polymerizing a vinyl chloride monomer in the presence of an acrylic-containing resin> The resin emulsion of a composite resin obtained by polymerizing a vinyl chloride monomer in the presence of an acrylic-containing resin is not particularly limited, but examples include emulsions of vinyl chloride-acrylic composite resins obtained by polymerizing a monomer primarily composed of an acrylic monomer in the first stage of a multistage emulsion polymerization method, and polymerizing a monomer primarily composed of vinyl chloride monomer in the second stage and thereafter. The "monomer primarily composed of an acrylic monomer" and the "monomer primarily composed of vinyl chloride monomer" may be the same monomers as those described in the above-mentioned <Resin emulsion of a composite resin obtained by polymerizing an acrylic monomer in the presence of a vinyl chloride resin>. Additionally, surfactants, polymerization initiators, and the like used in emulsion polymerization may also be appropriately selected and employed.

[0065] Resin emulsions of resins obtained by polymerizing vinyl chloride monomers in the presence of the acrylic-containing resin are well known in the art, and any conventionally known resin emulsions can be used as appropriate. Suitable examples include the resin emulsions described in Japanese Patent No. 6247317.

[0066] <Resin Emulsion of Composite Resin Prepared by Polymerizing Vinyl Chloride Monomer in the Presence of Styrene-(Meth)acrylic Acid Ester Oligomer and / or (Meth)acrylic Acid Ester Oligomer> Resin emulsions of composite resins prepared by polymerizing vinyl chloride monomer in the presence of styrene-(meth)acrylic acid ester oligomer and / or (meth)acrylic acid ester oligomer are not particularly limited, but examples include emulsions of vinyl chloride-acrylic composite resins obtained by polymerizing a monomer primarily composed of vinyl chloride monomer in a container containing commercially available styrene-(meth)acrylic acid ester oligomer and / or (meth)acrylic acid ester oligomer. The "monomer primarily composed of vinyl chloride monomer" may be the same monomer as described in the above-mentioned <Resin Emulsion of Composite Resin Prepared by Polymerizing Acrylic Monomer in the Presence of Vinyl Chloride Resin>. Surfactants, polymerization initiators, and the like used in emulsion polymerization may also be appropriately selected and employed.

[0067] The resin emulsion of the resin obtained by polymerizing a vinyl chloride monomer in the presence of the styrene-(meth)acrylic acid ester oligomer and / or the (meth)acrylic acid ester oligomer is known in the art, and a conventionally known resin emulsion can be used as appropriate. Suitable examples include the resin emulsion described in International Publication No. 2010-140647.

[0068] [1-1-1-2. Vinyl chloride resin emulsion] The vinyl chloride resin emulsion is not particularly limited, but examples thereof include emulsions of vinyl chloride resin obtained by polymerizing a monomer mainly composed of vinyl chloride monomer in an emulsion polymerization method.

[0069] The "monomer mainly composed of vinyl chloride monomer" may be the same as the monomer described in the above <Resin emulsion of composite resin obtained by polymerizing acrylic monomer in the presence of vinyl chloride resin>. In addition, surfactants, polymerization initiators, etc. used in emulsion polymerization may also be appropriately selected and used.

[0070] [1-1-1-3. Vinyl chloride-acrylic copolymer emulsion] The vinyl chloride-acrylic copolymer emulsion is not particularly limited, but examples include emulsions of vinyl chloride-acrylic copolymers obtained by copolymerizing a monomer mainly composed of vinyl chloride monomer with a monomer mainly composed of acrylic monomer in an emulsion polymerization method. The "monomer mainly composed of acrylic monomer" and the "monomer mainly composed of vinyl chloride monomer" may be the same monomers as those described in the above-mentioned <Resin emulsion of composite resin obtained by polymerizing acrylic monomer in the presence of vinyl chloride resin>. Furthermore, surfactants, polymerization initiators, and the like used in emulsion polymerization may also be appropriately selected and employed.

[0071] The vinyl chloride-acrylic copolymer emulsion is known in the art, and any conventionally known resin emulsion can be used as appropriate. Suitable examples include the resin emulsions described in JP-A-10-176132.

[0072] [1-1-2. Acrylic Resin Emulsion] The acrylic resin emulsion is not particularly limited, but examples thereof include emulsions of acrylic resins obtained by polymerizing monomers mainly composed of acrylic monomers in an emulsion polymerization method. Here, the acrylic resin is a resin obtained by polymerizing monomers that do not contain vinyl chloride monomer or that contain only a small amount of vinyl chloride monomer (10 parts by weight or less when the total amount of the monomer mixture is 100 parts by weight).

[0073] The "monomer mainly composed of an acrylic monomer" can be the same as the monomer described in the above-mentioned <Resin emulsion of a composite resin obtained by polymerizing an acrylic monomer in the presence of a vinyl chloride resin>. Furthermore, the emulsion polymerization method and the surfactant, polymerization initiator, etc. used can be appropriately selected and adopted from the method described in [Step 2] of the above-mentioned <Resin emulsion of a composite resin obtained by polymerizing an acrylic monomer in the presence of a vinyl chloride resin>. Therefore, emulsion polymerization can be carried out in a single stage or in multiple stages. When the emulsion polymerization is carried out in multiple stages, the composition of the monomer mixture can be changed in each stage.

[0074] The acrylic resin emulsion is known in the art, and a conventionally known resin emulsion can be used as appropriate. Suitable examples include the resin emulsions described in JP-A-2006-070236 and WO 2018-088560.

[0075] These acrylic resin emulsions can also be used if they are commercially available from various companies, and examples thereof include Boncoat (registered trademark) and Watersol (registered trademark) manufactured by DIC Corporation; Acryset (registered trademark) and U-Double (registered trademark) manufactured by Nippon Shokubai Co., Ltd.; Polysol (registered trademark) manufactured by Showa Denko K.K.; Yodozole (registered trademark) and Kanebinol (registered trademark) manufactured by Henkel Japan; Polytron (registered trademark) and Polydurex (registered trademark) manufactured by Asahi Kasei Chemicals Corporation; Rikabond (registered trademark) and Mowinyl (registered trademark) manufactured by Japan Coating Resins Co., Ltd.; Kanekazemurac (registered trademark) manufactured by Kaneka Corporation; Primal (registered trademark) manufactured by The Dow Chemical Company; Acronal (registered trademark) and Joncryl (registered trademark) manufactured by BASF; and Neocryl (registered trademark) and Bayhydrol (registered trademark) manufactured by Covestro AG.

[0076] In the explanation of the vinyl chloride-acrylic composite resin emulsion, it was explained that it is more preferable to use an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group, and further include (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule. For the same reason, it is also more preferable for the other (A) component to use an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group, and further include (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule.

[0077] Among them, from the viewpoint of the balance between film-forming properties and film hardness, the vinyl chloride resin emulsion is more preferably a vinyl chloride-acrylic composite resin emulsion, and more preferably a resin emulsion of a composite resin obtained by polymerizing an acrylic monomer in the presence of a vinyl chloride resin.

[0078] 1-2. Component (B) The aqueous ink composition according to one embodiment of the present invention contains an aqueous polyester resin as component (B). In this specification, the term "aqueous polyester resin" includes the following (i) and (ii):

[0079] (i) Water-soluble or dispersible polyester resins (ii) Polyester resins that are forcibly emulsified or dispersed in water by adding an emulsifier or the like and performing mechanical stirring The polyester resins in (i) can also be said to be hydrophilic polyester resins. The polyester resins in (ii) can also include hydrophobic polyester resins.

[0080] The "aqueous polyester resin" may be a polyester resin containing a hydrophilic group such as a carboxylic acid (salt) group, a sulfonic acid (salt) group, or a polyoxyethylene group in the molecule to impart water solubility or water dispersibility.

[0081] The aqueous polyester resin may be prepared by appropriately selecting a diol component and a dicarboxylic acid component as raw materials, and may further comprise a copolymer of a compound containing a polycarboxylic acid (salt) having three or more carboxylic acids; a compound containing a sulfonic acid (salt) group such as a sulfonate salt of a dicarboxylic acid; or a compound containing a polyoxyethylene group, in order to impart water solubility or water dispersibility.

[0082] Aqueous polyester resins are known in the art, and conventionally known aqueous polyester resins can be used as appropriate. Suitable examples of aqueous polyester resins include those described in JP-A-61-37815, WO 2016 / 043683, WO 2017 / 158643, etc.

[0083] As the aqueous polyester resin, commercially available products on the market may be used. Examples of commercially available products include the Plus Coat series (Plus Coat Z-221, Z-446, Z-561, Z-565, Z-880, Z-3310, RZ-105, RZ-507, Z-730, Z-760, Z-592, Z-687, Z-690) manufactured by GOO Chemical Industry Co., Ltd., and aqueous polyester resin coating agents (GX-1471, GX- 1473, GX-1448, GX-1486, GX-1487, GX-1488, GX-1489, GX-1481, GX-1482, GX-1483, GX-1484, GX-1485, GX-1490); Vylonal (registered trademark) MD-1200, MD-1500, MD-2000, MD-1480, MD-1985 manufactured by Toyobo Co., Ltd.; and the Eastek polymer dispersion series (Eastek 1000, 1100, 1200, 1300, 1400) manufactured by Eastman Chemical Company.

[0084] The acid value of the aqueous polyester resin is preferably in the range of 2 to 100 mgKOH / g, more preferably in the range of 20 to 80 mgKOH / g, and particularly preferably in the range of 35 to 68 mgKOH / g. An acid value of 2 mgKOH / g is preferable because it improves dispersibility or solubility in water and provides substrate adhesion. Furthermore, an acid value of 100 mgKOH / g or less is preferable because it provides excellent storage stability when made into an ink. Furthermore, from the viewpoints of substrate adhesion and storage stability, a carboxyl group is more preferable as the functional group that imparts the acid value.

[0085] [1-3. Component (D)] The aqueous ink composition according to one embodiment of the present invention may contain a polyolefin resin emulsion as component (D). By including component (D), the aqueous ink composition according to one embodiment of the present invention preferably contains component (D) because this improves adhesion to polyolefin substrates.

[0086] The polyolefin resin emulsion is an emulsion of a polyolefin resin, and the polyolefin resin is not particularly limited, but examples thereof include polypropylene, ethylene-propylene copolymer, and ethylene-propylene-butene copolymer.

[0087] The polyolefin resin may be modified by a method selected from chlorination-modification, acrylic modification, and maleic anhydride modification, and is more preferably a chlorination-modified polyolefin resin emulsion, and particularly preferably a chlorinated polypropylene resin emulsion.

[0088] The polyolefin-based resin emulsion is known in the art, and any conventionally known polyolefin-based resin emulsion can be used as appropriate. Suitable examples include the resin emulsions described in JP-A-2013-193324 and JP-A-10-298233.

[0089] The polyolefin resin may be a commercially available product on the market. Examples of commercially available products include the Superchlor (registered trademark) series manufactured by Nippon Paper Industries Co., Ltd. (Superchlor (registered trademark) E-415, E-480T, E-604 (maleic anhydride modified, chlorinated modified), Superchlor (registered trademark) E-723 (chlorinated modified), etc.), and the Auroren (registered trademark) series manufactured by Nippon Paper Industries Co., Ltd. (non-chlorine-based polyolefin, Auroren (registered trademark) AE-301, AE-202 (maleic anhydride, acrylic modified), Auroren (registered trademark) S-6375 (maleic anhydride modified), etc.). Examples of such a polyurethane include: Hardlen (registered trademark) EH-801J, EW-5515, EW-5303, EW-5250 (maleic anhydride-modified, chlorinated modified), NA-1015, NA-1100, NA-4002, NA-3002, NZ-1001, NZ-1004, NZ-1015, NZ-1029 (maleic anhydride-modified), manufactured by Toyobo Co., Ltd.; and the ZAIXXEN (registered trademark) series (ZAIXXEN (registered trademark) L, A, NC, N (acrylic modified), etc.) manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0090] [1-4. Component (G)] The aqueous ink composition according to one embodiment of the present invention may contain an alkali-soluble resin as component (G). By including component (G), the aqueous ink composition according to one embodiment of the present invention preferably further improves adhesion to polyamide substrates.

[0091] Here, the term "alkali-soluble resin" refers to a resin that is insoluble in water as it is, but dissolves in water under alkaline conditions. Here, "water-insoluble" means that the resin becomes cloudy or precipitates when added to water having a pH of 7 or less at 25°C. Furthermore, "under alkaline conditions" means that the pH exceeds 7.

[0092] Examples of the alkali-soluble resin include copolymer resins obtained by copolymerizing an ethylenically unsaturated carboxylic acid with an unsaturated monomer copolymerizable therewith. Specific examples of the alkali-soluble resin include styrene-(meth)acrylic acid copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-(meth)acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, isobutylene-maleic anhydride copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer, acrylic acid ester-methacrylic acid ester-(meth)acrylic acid copolymer, etc.

[0093] Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth)acrylate, 2-carboxypropyl (meth)acrylate, maleic anhydride, maleic acid monoalkyl ester, citraconic acid, citraconic anhydride, and citraconic acid monoalkyl ester. The ethylenically unsaturated carboxylic acid may be used alone or in combination of two or more. Among these, the ethylenically unsaturated carboxylic acid is more preferably acrylic acid, methacrylic acid, maleic acid, or itaconic acid.

[0094] The aforementioned component (A) may also contain an emulsion of a resin obtained by polymerizing a monomer mixture containing the aforementioned ethylenically unsaturated carboxylic acid, but such a resin differs from the alkali-soluble resin of component (G) in that it is insoluble in water under alkaline conditions.

[0095] The amount of the ethylenically unsaturated carboxylic acid used is preferably 5 to 60 parts by weight, more preferably 7 to 50 parts by weight, even more preferably 10 to 40 parts by weight, and particularly preferably 12 to 30 parts by weight, based on 100 parts by weight of the total amount of the monomer mixture constituting the alkali-soluble resin. A use amount of 5 parts by weight or more of the ethylenically unsaturated carboxylic acid is preferred because the alkali-soluble resin dissolves in water under alkaline conditions. A use amount of 60 parts by weight or less is also preferred from the viewpoints of the stability of the emulsion containing the alkali-soluble resin and the water resistance of the applied ink. Furthermore, an amount exceeding 60 parts by weight increases the viscosity of the emulsion after alkali-solubilization of the alkali-soluble resin.

[0096] The unsaturated monomer is not particularly limited as long as it is an unsaturated monomer copolymerizable with the ethylenically unsaturated carboxylic acid, and examples thereof include alkyl esters of acrylic acid or methacrylic acid having 1 to 18 carbon atoms (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, t-butyl (meth)acrylate, etc.); vinyl aromatics (e.g., styrene, 4-methylstyrene, α-methylstyrene, etc.); saturated carboxylic acid vinyl esters (e.g., vinyl acetate, vinyl propionate, etc.); monoolefinically unsaturated carboxylic acid amides (e.g., acrylamide, methacrylamide, etc.); N-alkyl and / or N-alkylol derivatives of monoolefinically unsaturated carboxylic acid amides (e.g., N-methylacrylamide, N-methylolacrylamide, etc.); ethylenically unsaturated carboxylic acids having a carbonyl group derived from a keto group or an aldehyde group. Examples of the monomer include saturated monomers (for example, acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, and vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, and vinyl butyl ketone)); monoolefinically unsaturated sulfonic acids (for example, vinyl sulfonic acid and methylacrylamidopropanesulfonic acid) and salts thereof; adducts of polyethylene glycol and methacrylic acid (Blemmer PE series: trade name, manufactured by NOF Corporation); adducts of polypropylene glycol and methacrylic acid (Blemmer PP series: trade name, manufactured by NOF Corporation); diolefinically unsaturated monomers (1,4-diacryloxybutane, divinylbenzene, and the like); acrylonitrile; hydroxyethyl acrylate; hydroxyethyl methacrylate; hydroxypropyl acrylate; hydroxypropyl methacrylate; glycidyl methacrylate; vinylidene chloride; vinyl chloride; and butadiene. The unsaturated monomers may be used alone or in combination of two or more kinds.

[0097] The use of an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group as the unsaturated monomer can improve adhesion to the film. Among the ethylenically unsaturated monomers having a carbonyl group derived from a keto group or an aldehyde group, diacetone acrylamide and diacetone methacrylamide are particularly preferred in terms of reactivity, availability, and economy.

[0098] The amount of the ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group used is preferably 0.1 to 10 parts by weight, and more preferably 1 to 5 parts by weight, relative to 100 parts by weight of the total monomer mixture constituting the alkali-soluble resin.

[0099] An alkali-soluble resin is obtained by using an ethylenically unsaturated monomer having a carbonyl group derived from a keto group or an aldehyde group as the unsaturated monomer, and then the obtained alkali-soluble resin is neutralized with an alkali to make it water-soluble. In this solution, or in the case of preparation by emulsion polymerization, in the emulsion, (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule can be added to impart crosslinkability, thereby improving the water resistance, solvent resistance, and adhesion of the resulting coating film, ink, etc.

[0100] Specific examples of the (C) hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule are as described above for the (A) component, and therefore further description will be omitted here.

[0101] The amount of the (C) hydrazine derivative having a hydrazino group or a semicarbazide group to be blended is preferably such that the total amount of functional groups selected from hydrazide groups, semicarbazide groups, and hydrazone groups is 0.01 mol to 2 mol, and more preferably 0.05 mol to 1.5 mol, per 1 mol of carbonyl groups in the alkali-soluble resin.

[0102] That is, the alkali-soluble resin has a carbonyl group derived from a keto group or an aldehyde group, and more preferably further contains (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule.

[0103] The weight-average molecular weight of the alkali-soluble resin is not limited thereto, but is preferably 1,000 to 60,000, more preferably 1,500 to 30,000, and even more preferably 2,000 to 25,000. An alkali-soluble resin having a weight-average molecular weight of 1,000 or more is preferred because it provides excellent pigment dispersion stability and excellent abrasion resistance to the resulting coating. Furthermore, an alkali-soluble resin having a weight-average molecular weight of 60,000 or less is preferred because it provides excellent handleability without a significant increase in viscosity.

[0104] Here, the weight average molecular weight is a weight average molecular weight measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0105] The Tg of the alkali-soluble resin is preferably 50° C. or higher in terms of the hardness of the resulting film.

[0106] When the alkali-soluble resin is produced by emulsion polymerization, the particle size does not need to be particularly considered because the resin is neutralized and water-soluble, but if the particle size is too small, the viscosity of the emulsion increases during polymerization, resulting in poor productivity. From this viewpoint, the particle size is preferably greater than 150 nm.

[0107] The method for producing the alkali-soluble resin is not particularly limited, and the resin can be produced by bulk polymerization, solution polymerization, emulsion polymerization, etc. Among these, emulsion polymerization is the most suitable, since it does not require steps such as drying, pulverization, solvent removal, and redissolution, and can perform the steps from polymerization to neutralization and water-solubilization in a continuous manner.

[0108] The alkali-soluble resin emulsion can be produced, for example, by emulsion polymerizing an unsaturated monomer mixture consisting of 5 to 60 parts by weight of the ethylenically unsaturated carboxylic acid and 40 to 95 parts by weight of an unsaturated monomer copolymerizable therewith in water in the presence of a surfactant and a chain transfer agent. The surfactant may be the same as those listed in the description of component (A).

[0109] Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; thioglycolic acid esters such as methyl thioglycolate, propyl thioglycolate and 2-ethylhexyl thioglycolate; β-mercaptopropionic acid esters such as methyl β-mercaptopropionate and octyl β-mercaptopropionate; and α-methylstyrene dimer.

[0110] The polymerization initiator used in the emulsion polymerization can be the same as those listed in the description of component (A).

[0111] The alkali-soluble resin may be a commercially available product on the market. Examples of commercially available products include Neocryl (registered trademark) B-817 (Tg: 64°C, Mw: 23,000) and Neocryl (registered trademark) B-890 (Tg: 85°C, Mw: 12,500) manufactured by Covestro AG, Germany, and Joncryl (registered trademark) 67 (Tg: 73°C, Mw: 12,500), Joncryl (registered trademark) 678 (Tg: 85°C, Mw: 8,500), Joncryl (registered trademark) 690 (Tg: 102°C, Mw: 16,500), Joncryl 682 (registered trademark) (Tg: 56°C, Mw: 1,700), Joncryl (registered trademark) 693 (Tg: 84°C, Mw: 6,000), and Joncryl (registered trademark) manufactured by BASF AG, Germany. JONCRYL (registered trademark) 819 (Tg: 57°C, Mw: 14,500), JONCRYL (registered trademark) JDX-C3000A (Tg: 65°C, Mw: 10,000), JONCRYL (registered trademark) JDX-C3080 (Tg: 134°C, Mw: 14,000), JONCRYL (registered trademark) HPD-196 (Tg: 85°C, Mw: 9,200), JONCRYL (registered trademark) HPD-96J (Tg: 102°C, Mw: 16,500), JONCRYL (registered trademark) 6610 (Tg: 85°C, Mw: 8,500), JONCRYL (registered trademark) JDX-6500 (Tg: 65°C, Mw: 10,000).

[0112] [1-5. Aqueous Ink Composition] An aqueous ink composition according to one embodiment of the present invention contains component (A) and component (B). By including component (A) and component (B), the aqueous ink composition according to one embodiment of the present invention exhibits improved adhesion to polyester substrates and polyamide substrates. The blending ratio of component (A) to component (B), based on the weight of the solids, is, but is not limited to, for example, 60 to 98:2 to 40, more preferably 60 to 95:5 to 40, and even more preferably 70 to 95:5 to 30. The solids content of each component can be calculated using the solids concentration measured by the method described in the examples in accordance with JIS K 6828-1:2003, Synthetic Resin Emulsions, Part 1: Determination of Nonvolatile Content. Alternatively, from the viewpoint of improving adhesion to polyester substrates and polyamide substrates while not adversely affecting adhesion to polyolefin substrates and polyvinyl chloride substrates, the ratio of component (A):component (B) may be 80-98:2-20, 85-98:2-15, 90-98:2-10, or 92-98:2-8.

[0113] In the aqueous ink composition, the solid contents of the components (A), (B), (D), and (G) contained in the aqueous ink composition can be determined in accordance with JIS K 6828-1:2003, Synthetic resin emulsions, Part 1: Determination of non-volatile content.

[0114] The aqueous ink composition according to one embodiment of the present invention further contains component (D) in addition to components (A) and (B), thereby improving adhesion to polyolefin substrates in addition to adhesion to polyester substrates and / or polyamide substrates. In such cases, the blending ratio of components (A), (B), and (D) is, but is not limited to, for example, 30-90:5-40:5-30 (A):5-30, more preferably 50-90:5-30:5-20 (A):5-20 (B):5-30:5-20 (D), based on the weight of the solids.

[0115] The aqueous ink composition according to one embodiment of the present invention further contains component (G) in addition to components (A) and (B), thereby improving adhesion to at least one of polyester substrates and polyamide substrates, as well as adhesion to polyolefin substrates, and further improving adhesion to polyamide substrates. In such cases, the blending ratio of components (A), (B), and (G) is, but is not limited to, for example, 30-90:5-40:1-20 (A):1-20 (G), more preferably 50-90:5-30:2-10 (A):1-10 (B):2-10 (G), based on the weight of the solids.

[0116] The aqueous ink composition according to one embodiment of the present invention further improves adhesion to polyamide substrates by further containing components (D) and (G) in addition to components (A) and (B). In such cases, the blending ratios of components (A), (B), (D), and (G) are, but are not limited to, for example, 30-90 (A): 5-40 (B): 5-30 (D): 1-20 (G), more preferably 50-90 (A): 5-30 (B): 5-20 (D): 2-10 (G), based on the weight of the solids.

[0117] Furthermore, an aqueous ink composition according to one embodiment of the present invention uses an emulsion containing, as component (A), a carbonyl group derived from a keto group or an aldehyde group, and (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule, and by including component (B), adhesion to not only polyester substrates but also polyolefin substrates and polyamide substrates is improved.

[0118] The aqueous ink composition according to one embodiment of the present invention preferably further contains a pigment (E).

[0119] The pigment is not particularly limited, but examples thereof include carbon black, phthalocyanine blue, quinacridone red, monoazo yellow, monoazo red, disazo orange, quinacridone magenta, dioxazine violet, phthalocyanine green, benzimidarozone, bismuth vanadate, naphthol red, titanium dioxide, calcium carbonate, kaolin clay, talc, barium sulfate, white carbon, red iron oxide, yellow ochre, and composite oxides.

[0120] Furthermore, self-dispersing pigments can also be used, which are made stably dispersible in water by chemically treating the surface of these pigments to add hydrophilic functional groups to the surface.

[0121] These pigments may be dispersed when preparing the ink, but commercially available pigment dispersions in which the pigments are dispersed in water in advance can also be used.

[0122] Typically, when applying an aqueous ink to a substrate, a primer, which is an undercoat paint, is applied to the substrate to improve adhesion, and then the aqueous ink composition is applied. However, with the aqueous ink composition according to one embodiment of the present invention, sufficient adhesion can be achieved without applying a primer. In other words, the aqueous ink composition according to one embodiment of the present invention does not require a primer.

[0123] [1-6. Printed matter] One aspect of the present invention also includes a printed matter obtained using the aqueous ink composition according to one embodiment of the present invention. The printed matter according to one embodiment of the present invention is obtained by printing (coating) the aqueous ink composition on a substrate.

[0124] The substrate is not particularly limited, but examples thereof include absorbent substrates such as paper, and poorly absorbent substrates such as resin. In particular, the aqueous ink composition according to one embodiment of the present invention has excellent adhesion to at least one film substrate selected from the group consisting of polyester substrates and polyamide substrates, and is therefore suitable for use with these substrates.

[0125] The method for applying the aqueous ink composition to a substrate is not limited to, but includes, for example, letterpress printing, flexographic printing, gravure printing, screen printing, inkjet printing, etc., and the aqueous ink composition is applied as, for example, flexographic ink, gravure ink, screen ink, inkjet ink, etc. The aqueous ink composition according to one embodiment of the present invention is particularly suitable for use as flexographic ink, gravure ink, and inkjet ink.

[0126] [2. Method for Producing Aqueous Ink Composition] The method for producing an aqueous ink composition according to one embodiment of the present invention is not particularly limited as long as it is a method for producing an aqueous ink composition containing (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin, and a method for producing a typical aqueous ink can be appropriately adopted. The method for producing an aqueous ink composition according to one embodiment of the present invention includes, for example, a step of blending (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin.

[0127] A method for producing an aqueous ink composition according to one embodiment of the present invention may include the step of producing the vinyl chloride resin emulsion (A) by carrying out the following steps 1 and 2. The following steps 1 and 2 are as described in [1. Aqueous ink composition].

[0128] [Step 1] A step of emulsion polymerizing a monomer mixture consisting of (a1) more than 90 parts by weight and 100 parts by weight or less of a vinyl chloride monomer and (a2) 0 to less than 10 parts by weight of an ethylenically unsaturated monomer copolymerizable with the vinyl chloride monomer (wherein the total amount of (a1) and (a2) is 100 parts by weight), to obtain a vinyl chloride resin; [Step 2] A step of emulsion polymerizing a monomer mixture consisting of (b1) 50 to 100 parts by weight of a (meth)acrylic acid alkyl ester and (b2) 0 to 50 parts by weight of an ethylenically unsaturated monomer copolymerizable with the (meth)acrylic acid alkyl ester (wherein the total amount of (b1) and (b2) is 100 parts by weight), in the presence of the vinyl chloride resin, to obtain an acrylic-containing resin.

[0129] For example, an aqueous ink composition can be produced by using an emulsion produced by emulsion polymerization as component (A) as is, blending component (A), component (B), and, if necessary, component (D) and / or component (G) with deionized water, a solvent, a surfactant, and / or a pigment dispersion, etc., so that the solid content of each component is the desired amount, and stirring the mixture.

[0130] In addition to deionized water, solvents, surfactants, pigment dispersions, etc., additives used in coating materials, such as film-forming aids, colloidal silica, plasticizers, dispersants, wetting agents, preservatives, antifreezing agents, light stabilizers, ultraviolet absorbers, antifoaming agents, and silane coupling agents, may also be added.

[0131] According to the above-described configuration, the aqueous ink composition according to one embodiment of the present invention can reduce the use of organic solvents and reduce the burden on the environment. Such effects also contribute to the achievement of Goal 6 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Ensure availability and sustainable management of water and sanitation for all."

[0132] <Summary> One embodiment of the present invention includes the following configuration.

[0133] [1] An aqueous ink composition containing (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin.

[0134] [2] The aqueous ink composition according to [1], wherein the (A) vinyl chloride resin emulsion and / or the acrylic resin emulsion has a carbonyl group derived from a keto group or an aldehyde group, and further contains (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule.

[0135] [3] The aqueous ink composition according to [1] or [2], further comprising (D) a polyolefin resin emulsion.

[0136] [4] The aqueous ink composition according to any one of [1] to [3], further comprising (E) a pigment.

[0137] [5] The aqueous ink composition according to any one of [1] to [4], wherein the aqueous polyester resin (B) has a carboxyl group.

[0138] [6] The aqueous ink composition according to claim 3, wherein the polyolefin resin emulsion (D) is a chlorinated polypropylene resin emulsion.

[0139] [7] The aqueous ink composition according to any one of [1] to [6], wherein the vinyl chloride resin emulsion is an emulsion of a composite resin obtained by carrying out the following steps 1 and 2: [Step 1] A step of emulsion-polymerizing a monomer mixture consisting of (a1) more than 90 parts by weight and 100 parts by weight or less of a vinyl chloride monomer and (a2) 0 to 10 parts by weight of an ethylenically unsaturated monomer copolymerizable with the vinyl chloride monomer (wherein the total amount of (a1) and (a2) is 100 parts by weight) to obtain a vinyl chloride resin; [Step 2] A step of emulsion-polymerizing a monomer mixture consisting of (b1) 50 to 100 parts by weight of a (meth)acrylic acid alkyl ester and (b2) 0 to 50 parts by weight of an ethylenically unsaturated monomer copolymerizable with the (meth)acrylic acid alkyl ester (wherein the total amount of (b1) and (b2) is 100 parts by weight) in the presence of the vinyl chloride resin to obtain an acrylic-containing resin.

[0140] [8] A printed matter obtained by printing the aqueous ink composition according to any one of [1] to [7] onto a substrate.

[0141] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0142] The methods for measuring the emulsion properties of the vinyl chloride resin emulsion, acrylic resin emulsion, and alkali-soluble resin used in the examples and comparative examples, as well as the methods for producing and evaluating the aqueous ink compositions obtained in the examples and comparative examples, are as follows. Furthermore, "parts" and "%" are by weight (parts by weight and % by weight) unless otherwise specified.

[0143] [Method for measuring emulsion properties of vinyl chloride resin emulsion, acrylic resin emulsion, and alkali-soluble resin] (Particle size distribution and average particle size) The particle size distribution and average particle size of the resin particles contained in the emulsion were measured using a particle size distribution measuring device ("Nanotrac Wave-EX150" manufactured by Microtrac-Bell Co., Ltd.) that uses dynamic light scattering. In the measurement, the emulsion was diluted to a concentration such that the loading index in sample loading was about 1, and the particle size distribution and average particle size were measured on a volume basis.

[0144] (Viscosity) The viscosity of the emulsion was measured using a BM type viscometer at a liquid temperature of 25° C. and 60 rpm.

[0145] (Minimum Film Formation Temperature) The minimum film formation temperature (hereinafter sometimes referred to as "MFT") of the emulsion was measured using an MFT tester TP-801LT manufactured by Tester Sangyo Co., Ltd.

[0146] (THF insolubles) The emulsion was thinly spread in a polyethylene container and dried in a dryer at 60°C for 16 hours to obtain a solid. The obtained solid was placed in a bag made of 200 mesh wire mesh, the weight (W1) of which had been measured in advance, and the total weight (W2) of the solid and the bag was measured. Thereafter, the bag containing the solid was immersed in tetrahydrofuran (THF) at room temperature for 16 hours. The bag was removed from the THF, dried in a dryer at 120°C for 1 hour, and allowed to cool to room temperature in a desiccator, and then the weight (W3) was measured.

[0147] The THF-insoluble content of the emulsion was calculated using the following formula: THF-insoluble content (%) = (W3 - W1) / (W2 - W1) x 100 (solid content concentration). Measurement was performed in accordance with JIS K 6828-1:2003, Synthetic resin emulsions, Part 1: Determination of nonvolatile content. Specifically, a certain amount of emulsion was poured into an aluminum container whose weight (w1) had been measured in advance, and the weight (w2) was measured. The container was then dried in a dryer at 120°C for 1 hour. The weight (w3) of the aluminum container containing the solid content after drying was measured. The solid content concentration was calculated using the following formula: Solid content (%) = (w3 - w1) / (w2 - w1) x 100 (weight average molecular weight). The weight average molecular weight of the alkali-soluble resin is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0148] [Method for producing aqueous ink composition] The components shown in Tables 4 to 6 were used, and deionized water was added to adjust the solids content of components (A) and (B), and when component (D) and / or (G) was included, the total solids content of components (A), (B), (D) and (G) was 7 parts per 100 parts of the final aqueous ink composition. Then, the solvent, surfactant and pigment dispersion shown in Table 1 were blended in the blending parts shown in Table 1, and the mixture was stirred for 15 minutes using a magnetic stirrer to produce an aqueous ink composition.

[0149] [Method for evaluating aqueous ink compositions] (Preparation of evaluation specimens) The aqueous ink compositions prepared were applied to various substrates listed in Table 2 using a No. 6 bar coater (thickness: 13.74 μm), dried in a dryer at 60° C. for 10 minutes, and then aged at 23° C. for 7 days to prepare evaluation specimens.

[0150] (Adhesion evaluation) When the substrate was OPP, PET, or Ny, a piece of cellophane tape (18 mm wide) about 10 cm long was attached to the surface of the evaluation specimen on which the ink composition had been applied, and the tape was firmly adhered. The left edge of the attached cellophane tape was forcefully peeled off, and the degree of peeling of the ink was observed.

[0151] When the substrate was PVC or plastic board: 25 grid-like cuts were made at 2 mm intervals with a cutter knife on the surface of the evaluation test specimen on which the ink composition had been applied, and cellophane tape was applied to the cuts and firmly adhered. The applied cellophane tape was forcefully peeled off from one end at a 45-degree angle, and the degree of ink peeling was observed.

[0152] The evaluation was based on the following criteria. Here, the "peeled area" refers to the area of ​​the portion of the peeled cellophane tape where ink was attached. The percentage of the peeled area (%) refers to the percentage of the "peeled area" relative to the area of ​​the cellophane tape attached to the evaluation specimen. A: No peeling at all. B: Peeled area is less than 30%. C: Peeled area is 30% or more but less than 70%. D: Peeled area is 70% or more but less than 100%. E: Completely peeled off.

[0153] Synthesis Example 1 [Step 1]: Production of vinyl chloride resin emulsion A polymerization vessel equipped with a stirrer was charged with 120 parts of deionized water, 0.094 parts of sodium formaldehyde sulfoxylate, 0.044 parts of sodium bicarbonate, 0.65 parts of sodium lauryl sulfate, 0.00165 parts of ferrous sulfate heptahydrate, and 0.00275 parts of disodium ethylenediaminetetraacetate (EDTA.2Na).

[0154] After the inside of the polymerization vessel was deoxygenated, 100 parts of vinyl chloride monomer was charged, the temperature of the mixture in the polymerization vessel was raised to 60°C, and an aqueous t-butyl hydroperoxide solution (0.1%) was continuously added as a polymerization initiator over 270 minutes so that the amount of t-butyl hydroperoxide became 0.012 parts.

[0155] A reactive surfactant, ADEKA REASOAP (registered trademark) SR-1025 (manufactured by ADEKA CORPORATION: 25% active ingredient), was added uniformly and continuously in the form of an aqueous solution (5%) so as to give 1.35 parts as the active ingredient over a period of 165 minutes starting 45 minutes after the initiation of polymerization (the time when the temperature of the mixture in the polymerization vessel reached 60°C).

[0156] When the internal pressure of the polymerization vessel was reduced to 0.5 MPa or less, the polymerization reaction was stopped. Unreacted vinyl chloride was removed to obtain a vinyl chloride resin emulsion (PVC-1).

[0157] The obtained vinyl chloride resin emulsion (PVC-1) had a polymerization conversion rate of 75%, an average particle size of 92 nm, and a solid content concentration of 33%. The average particle size and solid content concentration of the vinyl chloride resin emulsions (PVC-1 and PVC-2, described below) were measured using the same methods as those for measuring the average particle size and solid content concentration of vinyl chloride resin emulsions, etc. The polymerization conversion rate was calculated by dividing the solid content concentration by the theoretical solid content concentration, which would be obtained if all of the input monomers were polymerized. The values ​​shown are as follows:

[0158] Synthesis Example 2 [Step 1]: Production of vinyl chloride resin emulsion Polymerization was carried out in the same manner as in Synthesis Example 1, except that 0.1 parts of triallyl cyanurate (TAC) was mixed with an aqueous solution of ADEKA REASOAP (registered trademark) SR-1025 and added thereto for the purpose of introducing grafting sites with the acrylic resin in [Step 2], and unreacted vinyl chloride was removed to obtain a vinyl chloride resin emulsion (PVC-2).

[0159] The polymerization conversion rate of the vinyl chloride resin emulsion (PVC-2) was 74%, the average particle size was 85 nm, and the solid content was 33%. The amount of TAC is shown in Table 3. Here, the amount of TAC shown in Table 3, 0.06 parts, is the amount (parts by weight) contained in 50 parts of vinyl chloride resin, taking into account the polymerization conversion rate of the vinyl chloride resin.

[0160] [Production Example 1] [Step 2]: Production of Composite Resin Emulsion Into a polymerization vessel equipped with a stirrer were charged 157 parts (corresponding to 50 parts of vinyl chloride resin) of the vinyl chloride resin emulsion (PVC-1) produced in Synthesis Example 1, 0.6 parts of polyoxyethylene polyoxypropylene lauryl ether (Dai-ichi Kogyo Seiyaku Co., Ltd., Noigen (registered trademark) LP-180), and 7.5 parts of deionized water.

[0161] After the inside of the polymerization vessel was deoxygenated, the temperature of the mixture in the polymerization vessel was raised to 50°C, and then 0.028 parts of t-butyl hydroperoxide as a polymerization initiator and 0.011 parts of Bruggolite (registered trademark) FF-6 (manufactured by Bruggemann Chemical) as a reducing agent were added.

[0162] Furthermore, 50 parts of the acrylic monomer mixture shown in Production Example 1, Step 2 in Table 3 were emulsified with 0.75 parts of Aqualon (registered trademark) AR-1025 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: active ingredient 25%) as a reactive surfactant, 0.75 parts of Latemul (registered trademark) PD-430S (manufactured by Kao Corporation: active ingredient 25%) as an active ingredient, and 19 parts of deionized water (including the surfactant carried-in amount) by stirring to obtain a monomer emulsion. The obtained monomer emulsion was continuously and uniformly added to the polymerization vessel over 200 minutes. During the continuous addition of the monomer emulsion, 0.049 parts of t-butyl hydroperoxide as a polymerization initiator and 0.030 parts of Bruggolite (registered trademark) FF-6 as a reducing agent were additionally added to the polymerization vessel in eight divided portions.

[0163] After the continuous addition of the monomer emulsion was completed, post-polymerization was carried out for 90 minutes. The reaction mixture was then cooled to a liquid temperature of 40°C or below, neutralized with ammonia, and 0.5 parts of adipic acid dihydrazide (ADH) was added as a 10% aqueous solution per 100 parts of the total monomer mixture. The solids concentration of the reaction mixture was then adjusted to 40% with deionized water, yielding a composite resin emulsion (HB-1A).

[0164] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, and THF-insoluble content) of the resulting composite resin emulsion (HB-1A) were measured. The results, along with the glass transition temperatures of the vinyl chloride resin polymerized in step 1 and the acrylic-containing resin polymerized in step 2, are shown in Table 3.

[0165] [Production Example 2] [Step 2]: Production of Composite Resin Emulsion A composite resin emulsion (HB-2A) was obtained by the same procedure as in Production Example 1, except that the vinyl chloride resin emulsion (PVC-2) produced in Synthesis Example 2 was used instead of the vinyl chloride resin emulsion (PVC-1), that the acrylic monomer mixture shown in Production Example 2, Step 2 in Table 3 was used as the acrylic monomer mixture, and that instead of adding 0.5 parts of adipic acid dihydrazide (ADH) as a 10% aqueous solution to 100 parts of the total monomer mixture and adjusting the solids concentration of the reaction mixture with deionized water to 40%, 1.0 part of adipic acid dihydrazide (ADH) as a 10% aqueous solution to 100 parts of the total monomer mixture was added and the solids concentration of the reaction mixture was adjusted to 38% with deionized water.

[0166] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, and THF-insoluble content) of the resulting composite resin emulsion (HB-2A) were measured. The results, along with the glass transition temperatures of the vinyl chloride resin polymerized in step 1 and the acrylic-containing resin polymerized in step 2, are shown in Table 3.

[0167] [Production Example 3] [Step 2]: Production of composite resin emulsion A composite resin emulsion (HB-3) was obtained by performing the same operation as in Production Example 1, except that the acrylic monomer mixture shown in Production Example 3, Step 2 in Table 3 was used as the acrylic monomer mixture and that adipic acid dihydrazide (ADH) was not added.

[0168] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, and THF-insoluble content) of the resulting composite resin emulsion (HB-3) were measured. The results, along with the glass transition temperatures of the vinyl chloride resin polymerized in step 1 and the acrylic-containing resin polymerized in step 2, are shown in Table 3.

[0169] The composite resin emulsions obtained in Production Examples 1, 2, and 3 all had a single-peak particle size distribution, and the average particle size increased proportionally to the amount of added monomer, suggesting that vinyl chloride resin and acrylic resin coexist within the same particle. In other words, composite particles of vinyl chloride resin and acrylic resin were obtained.

[0170] The composite resin emulsions obtained in Production Examples 1, 2, and 3 exhibited a lower minimum film-forming temperature and better film-forming properties than the acrylic resin emulsion in Production Example 4 (described later) obtained by multistage polymerization using only an acrylic resin, despite the same Tg set in Step 1. Furthermore, a comparison between Production Examples 1 and 2 showed that the THF-insoluble content was further increased by introducing (F) a compound having at least two non-conjugated double bonds into the vinyl chloride resin.

[0171] In Production Examples 1, 2 and 3, the Tg of the acrylic resin was −20° C. or lower, so that a decrease in the minimum film-forming temperature (MFT) was observed, and film-forming properties were improved.

[0172] [Production Example 4]: Production of acrylic resin emulsion (two-stage emulsion polymerization) [Step 1] A polymerization vessel equipped with a stirrer was charged with 76 parts of deionized water, 0.0125 parts of sodium bicarbonate, 0.44 parts of sodium lauryl sulfate, and 1 / 10 of 50 parts of the monomer mixture shown in Production Example 4, Step 1 in Table 3.

[0173] After the inside of the polymerization vessel was deoxygenated, the temperature of the mixture in the polymerization vessel was raised to 50°C, and 0.035 parts of polymerization initiator t-butyl hydroperoxide, 0.0007 parts of ferrous sulfate heptahydrate, 0.0028 parts of disodium ethylenediaminetetraacetate (EDTA 2Na), and 0.35 parts of a reducing agent Bruggolite (registered trademark) FF-6 were added, followed by stirring for 30 minutes.

[0174] Next, 0.021 parts of polymerization initiator t-butyl hydroperoxide and 0.01125 parts of reducing agent Bruggolite (registered trademark) FF-6 were added to the polymerization vessel. To the remaining 9 / 10 of the 50 parts of the monomer mixture shown in Production Example 3, Step 1 in Table 3, 1.8 parts of reactive surfactant Adeka Reasoap (registered trademark) SR-1025 as an active ingredient, 0.6 parts of Noigen (registered trademark) LP-180, and 19 parts of ion-exchanged water (including the surfactant carried-in amount) were added and emulsified by stirring to obtain a monomer emulsion. The obtained monomer emulsion was continuously and uniformly added to the polymerization vessel over 180 minutes. During the continuous addition of the monomer emulsion, 0.049 parts of a polymerization initiator t-butyl hydroperoxide and 0.040 parts of a reducing agent Bruggolite® FF-6 were additionally added to the polymerization vessel in four divided portions.

[0175] [Step 2] Next, 0.028 parts of t-butyl hydroperoxide as a polymerization initiator and 0.011 parts of Bruggolite (registered trademark) FF-6 as a reducing agent were added to the polymerization vessel.

[0176] To 50 parts of the monomer mixture shown in Production Example 4, Step 2 in Table 3, 0.75 parts of the reactive surfactant Aqualon (registered trademark) AR-1025 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: active ingredient 25%), 0.75 parts of Latemul (registered trademark) PD-430S (manufactured by Kao Corporation: active ingredient 25%), and 19 parts of deionized water (including the surfactant) were added and emulsified by stirring to obtain a monomer emulsion. The obtained monomer emulsion was continuously and uniformly added to the polymerization vessel over 200 minutes. During the continuous addition of the monomer emulsion, 0.049 parts of t-butyl hydroperoxide and 0.030 parts of Bruggolite (registered trademark) FF-6 were additionally added to the polymerization vessel in eight divided additions.

[0177] After the addition of the monomer emulsion was completed, post-polymerization was carried out for 90 minutes. Thereafter, the liquid temperature of the reaction mixture was cooled to 40°C or less, and neutralization was carried out with ammonia. 0.5 parts of adipic acid dihydrazide (ADH) was added as a 10% aqueous solution per 100 parts of the total monomer mixture. Thereafter, the solids concentration of the reaction mixture was adjusted to 40% with deionized water, and an acrylic resin emulsion (AC-1A) was obtained.

[0178] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, THF-insoluble content) of the resulting acrylic resin emulsion (AC-1A) were measured. The results, as well as the glass transition temperatures of the acrylic-containing resin polymerized in step 1 and the acrylic-containing resin polymerized in step 2, are shown in Table 3.

[0179] [Production Example 5]: Production of acrylic resin emulsion (two-stage emulsion polymerization) An acrylic resin emulsion (AC-2A) was obtained by performing the same operation as in Production Example 4, except that the monomer composition in [Step 1] was changed to the monomer composition shown in Production Example 5, Step 1 in Table 3, and the monomer composition in [Step 2] was changed to the monomer composition shown in Production Example 5, Step 2 in Table 3.

[0180] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, THF-insoluble content) of the resulting acrylic resin emulsion (AC-2A) were measured. The results, as well as the glass transition temperatures of the acrylic-containing resin polymerized in step 1 and the acrylic-containing resin polymerized in step 2, are shown in Table 3.

[0181] [Production Example 6]: Production of acrylic resin emulsion (single-stage emulsion polymerization) To 100 parts of the monomer mixture shown in Production Example 6, Step 1 in Table 3 (including 3 parts of methacrylic acid), 1.6 parts as an active ingredient of Adeka Reasop (registered trademark) SR-1025 (manufactured by ADEKA Corporation: active ingredient content: 25%) as a reactive surfactant and 41 parts of water (including the surfactant carried-in amount) were added and emulsified by stirring to obtain a monomer emulsion.

[0182] A polymerization vessel equipped with a stirrer was charged with 90 parts of deionized water, 0.0125 parts of sodium bicarbonate, 0.1 parts of sodium lauryl sulfate, and 1 / 20 of the obtained monomer emulsion. The inside of the polymerization vessel was deoxygenated, and then the temperature of the mixture in the polymerization vessel was raised to 50°C.

[0183] 0.035 parts of t-butyl hydroperoxide as a polymerization initiator, 0.0007 parts of ferrous sulfate heptahydrate, 0.0028 parts of disodium ethylenediaminetetraacetate (EDTA 2Na), and 0.035 parts of Bruggolite (registered trademark) as a reducing agent were added to the polymerization vessel, and the mixture was stirred for 30 minutes.

[0184] Further, the remaining 19 / 20 of the monomer emulsion was uniformly and continuously added to the polymerization vessel over 285 minutes. During the continuous addition of the monomer emulsion, 0.0857 parts of t-butyl hydroperoxide as a polymerization initiator and 0.050 parts of Bruggolite (registered trademark) FF-6 as a reducing agent were additionally added to the polymerization vessel in eight divided portions.

[0185] After the addition of the monomer emulsion was completed, polymerization was carried out for 90 minutes. Thereafter, the liquid temperature of the reaction mixture was cooled to 40°C or below, and neutralization was carried out with ammonia. 0.5 parts of adipic acid dihydrazide (ADH) was added as a 10% aqueous solution per 100 parts of the total monomer mixture. Thereafter, the solids concentration of the reaction mixture was adjusted to 40% with deionized water, and an acrylic resin emulsion (AC-3A) was obtained.

[0186] The emulsion properties (average particle size, particle size distribution, viscosity, MFT, THF-insoluble content) of the obtained acrylic resin emulsion (AC-3A) were measured. The results and the glass transition temperature of AC-3A are shown in Table 3.

[0187] Even when the Tg was set to 0° C., the MFT was higher than that of the composite emulsion (overall average Tg: 19° C.), and the film-forming properties were inferior.

[0188] [Production Example 7]: Production of alkali-soluble resin To 100 parts of the monomer shown in Production Example 7, Step 1 in Table 3 (of which 18.5 parts of methacrylic acid was used), and 4 parts of a chain transfer agent mixture, 1.56 parts as an active ingredient of reactive surfactant AQUALON (registered trademark) AR-1025 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: active ingredient 25%), 1.56 parts as an active ingredient of LATEMULL (registered trademark) PD-430S (manufactured by Kao Corporation: active ingredient 25%), and 52.9 parts of deionized water (including the surfactant carried-in amount) were added and emulsified by stirring to obtain a monomer emulsion.

[0189] A polymerization vessel equipped with a stirrer was charged with 97 parts of deionized water, 0.013 parts of sodium bicarbonate, and 1 / 20 of the obtained monomer emulsion, and the inside of the polymerization vessel was deoxygenated, and then the temperature of the mixture in the polymerization vessel was raised to 50°C.

[0190] 0.36 parts of t-butyl hydroperoxide as a polymerization initiator, 0.0007 parts of ferrous sulfate heptahydrate, 0.0028 parts of disodium ethylenediaminetetraacetate (EDTA 2Na), and 0.42 parts of Bruggolite (registered trademark) as a reducing agent were added to the polymerization vessel, and the mixture was stirred for 30 minutes.

[0191] Further, the remaining 19 / 20 of the monomer emulsion was uniformly and continuously added to the polymerization vessel over 190 minutes. During the continuous addition of the monomer emulsion, 0.65 parts of t-butyl hydroperoxide as a polymerization initiator and 0.35 parts of Bruggolite (registered trademark) FF-6 as a reducing agent were additionally added to the polymerization vessel in six divided portions.

[0192] After the addition of the monomer emulsion was completed, polymerization was carried out for 90 minutes. Thereafter, the liquid temperature of the reaction mixture was cooled to 40°C or less, and neutralized with ammonia. 1.0 parts of adipic acid dihydrazide (ADH) was added as a 10% aqueous solution per 100 parts of the total monomer mixture to obtain an alkali-soluble resin (WS-1A).

[0193] The properties (average particle size, particle size distribution, weight average molecular weight, viscosity, MFT, THF insoluble content) of the obtained alkali-soluble resin (WS-1A) were measured. The results and the glass transition temperature of WS-1A are shown in Table 3.

[0194] [Comparative Examples 1 to 6, Examples 1 to 19] Aqueous ink compositions were produced using the components shown in Tables 4 to 6 in the amounts shown in Tables 4 to 6, and the adhesion of the resulting aqueous ink compositions was evaluated. The results are shown in Tables 4 to 6.

[0195] In Tables 4 to 6, "XK-190" listed as component (A), "Z-730," "MD-1480," and "Eastek 1100" listed as component (B), and "EW-5303" listed as component (D) are the following commercially available products. "XK-190": NeoCryl (registered trademark) XK-190 (acrylic resin emulsion manufactured by COVESTRO) "Z-730": Plascoat Z-730 (water-soluble polyester resin manufactured by GOO Chemical Industry Co., Ltd.) "MD-1480": Vylonal (registered trademark) MD-1480 (water-dispersible polyester resin manufactured by Toyobo Co., Ltd.) "Eastek 1100": Eastek 1100 polymer dispersion (water-dispersible polyester resin manufactured by Eastman Chemical Company, USA) "EW-5303": Hardlen (registered trademark) EW-5303 (water dispersion of maleic anhydride-chlorinated modified polyolefin resin manufactured by Toyobo Co., Ltd.) In addition, in Tables 4 to 6, the amount of each component is the ratio of the solid content of each component, and the unit of each amount is "wt%".

[0196] As shown in Table 5, the aqueous ink compositions of Examples 1 to 6, which contain a vinyl chloride-acrylic composite resin emulsion (HB-1A) and an aqueous polyester resin, tend to have superior adhesion to PET and also superior adhesion to Ny, compared to the aqueous ink composition of Comparative Example 1, which contains only HB-1A.

[0197] Furthermore, a comparison of the aqueous ink composition of Example 2 with the aqueous ink compositions of Examples 5 and 6 shows that the addition of (D) a polyolefin resin emulsion to the aqueous ink composition also improves adhesion to OPP and plastic board. Furthermore, a comparison of the aqueous ink composition of Example 5 with the aqueous ink composition of Example 6 shows that the addition of (G) an alkali-soluble resin to an aqueous ink composition containing components (A), (B), and (D) further improves adhesion to Ny.

[0198] As shown in Table 5, the aqueous ink composition of Example 7, which contains a vinyl chloride-acrylic composite resin emulsion (HB-2A) containing TAC, a compound having at least two non-conjugated double bonds (F), and an aqueous polyester resin, has superior adhesion to PVC in addition to adhesion to PET and Ny, compared to the aqueous ink composition of Example 3, which contains HB-1A without TAC and an aqueous polyester resin in the same blend ratio.

[0199] As shown in Table 5, the aqueous ink compositions of Examples 8 to 13, which contain a vinyl chloride-acrylic composite resin emulsion (HB3) and an aqueous polyester resin, tend to have superior adhesion to PET and also superior adhesion to Ny, compared to the aqueous ink composition of Comparative Example 2, which contains only HB3.

[0200] Furthermore, a comparison between the aqueous ink composition of Example 8 and the aqueous ink composition of Example 12, and a comparison between the aqueous ink composition of Example 9 and the aqueous ink composition of Example 10, reveals that the addition of a polyolefin resin emulsion (D) to an aqueous ink composition containing components (A) and (B) also improves adhesion to OPP and plastic board.

[0201] As shown in Table 6, the aqueous ink compositions of Examples 14 to 17, which contained an acrylic resin emulsion (AC-1A, AC-2A, AC-3A, XK-190) and an aqueous polyester resin, tended to have excellent adhesion to PET and also excellent adhesion to Ny, compared to the aqueous ink compositions of Comparative Examples 3 to 6, which contained only the corresponding acrylic resin emulsion.

[0202] As shown in Table 6, the aqueous ink compositions of Examples 18 and 19, each containing a vinyl chloride-acrylic composite resin emulsion (HB-1A) and an aqueous polyester resin (MD-1480, Eastec 1100), tend to have superior adhesion to PET and also superior adhesion to Ny, compared to the aqueous ink composition of Comparative Example 1, which contains only HB-1A.

[0203] According to one embodiment of the present invention, it is possible to provide an aqueous ink composition that has excellent adhesion to at least one film substrate selected from polyester substrates and polyamide substrates. Therefore, the aqueous ink composition according to one embodiment of the present invention is very useful as a paint or ink that can be used on a variety of substrates and can be used in a wide range of industrial fields.

Claims

1. An aqueous ink composition containing (A) a vinyl chloride resin emulsion and / or an acrylic resin emulsion, and (B) an aqueous polyester resin.

2. The aqueous ink composition according to claim 1, wherein the (A) vinyl chloride resin emulsion and / or the acrylic resin emulsion has a carbonyl group derived from a keto group or an aldehyde group, and further contains (C) a hydrazine derivative having at least two hydrazino groups or semicarbazide groups per molecule.

3. The aqueous ink composition according to claim 1 or 2, further comprising (D) a polyolefin resin emulsion.

4. The aqueous ink composition according to claim 1 or 2, further comprising (E) a pigment.

5. The aqueous ink composition according to claim 1 or 2, wherein the aqueous polyester resin (B) has a carboxyl group.

6. The aqueous ink composition according to claim 3, wherein the polyolefin resin emulsion (D) is a chlorinated polypropylene resin emulsion.

7. The aqueous ink composition according to claim 1 or 2, wherein the vinyl chloride resin emulsion is a composite resin emulsion obtained by carrying out the following steps 1 and 2: [Step 1] A step of emulsion-polymerizing a monomer mixture consisting of (a1) more than 90 parts by weight and 100 parts by weight or less of a vinyl chloride monomer and (a2) 0 to 10 parts by weight of an ethylenically unsaturated monomer copolymerizable with the vinyl chloride monomer (wherein the total amount of (a1) and (a2) is 100 parts by weight) to obtain a vinyl chloride resin; [Step 2] A step of emulsion-polymerizing a monomer mixture consisting of (b1) 50 to 100 parts by weight of a (meth)acrylic acid alkyl ester and (b2) 0 to 50 parts by weight of an ethylenically unsaturated monomer copolymerizable with the (meth)acrylic acid alkyl ester (wherein the total amount of (b1) and (b2) is 100 parts by weight) in the presence of the vinyl chloride resin to obtain an acrylic-containing resin.

8. A printed matter obtained by printing the aqueous ink composition according to claim 1 or 2 onto a substrate.

Images